Environment International 63 (2014) 149–162 Contents lists available at ScienceDirect Environment International journal homepage: www.elsevier.com/locate/envint Review Literature review of baseline study for risk analysis — The landﬁll leachate case T.E. Butt a,⁎,1, H.M. Gouda c, M.I. Baloch d, P. Paul e, A.A. Javadi b, A. Alam f a Centre of Water Systems (CWS), College of Engineering, Mathematics & Physical Sciences, The University of Exeter, Harrison Building, North Park Road, Exeter, EX4 4QF England, UK Department of Engineering, College of Engineering, Mathematics & Physical Sciences (CEMPS), The University of Exeter, Harrison Building, North Park Road, Exeter, EX4 4QF England, UK Department of Geography and Environmental Management, University of the West of England, Coldharbour Lane, Bristol, BS16 1QY England, UK d Utilities Business Unit, Jacobs, 1180 Eskdale Road, Winnersh, Wokingham, RG41 5TU England, UK e School of Engineering and Design, Brunel University, Uxbridge, UB8 3PH England, UK f Sustainable Development Study Center, Government College University, Katchery Road, Lahore, Pakistan b c a r t i c l e i n f o Article history: Received 26 January 2013 Accepted 23 September 2013 Available online 30 November 2013 Keywords: Baseline study Risk analysis Risk assessment Preliminary investigation Waste disposal sites Landﬁll leachate a b s t r a c t There is growing awareness and public concern about environmental impacts of waste management and disposal. Environmental policy instruments have been strengthened and associated governmental programmes have increased in recent years, resulting in high level strategies for waste management. Risk assessment is now an essential tool in the prioritisation of environmental and human health protection. However, regulators need to compare the full range of risks on a sound and consistent basis. Comparing risks from such diverse sources poses a signiﬁcant challenge, and traditional hazard and risk assessments are no longer sufﬁcient. Consideration now needs to be given to a much wider range of factors if risk assessment is to be used as an aid to more integrated decision-making process. For this purpose, baseline study – the foundation of risk assessment – can play a crucial role. To date limited research has been conducted on the need, parameters, requirements, and constituents of baseline study particularly in the context of how, why, and what information is to be collated in order to render risk assessments more appropriately integrated and complete. To establish the ‘state-of-the-art’ of baseline study, this paper comprehensively reviews the literature regarding environmental risk assessment in general terms, and then proceeds to review work that is speciﬁcally related to landﬁlls and landﬁll leachate, thereby identifying knowledge gaps and shortfall areas. This review concludes that a holistic baseline study procedure for waste disposal sites, which risk assessors could use for carrying out risk analyses speciﬁcally for landﬁll leachate, does not as yet exist. © 2013 Published by Elsevier Ltd. Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1. Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2. Landﬁlls and risk assessment . . . . . . . . . . . . . . . . . . . . 1.3. Research aims and methodology . . . . . . . . . . . . . . . . . . 1.3.1. Aims . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.2. Methodology . . . . . . . . . . . . . . . . . . . . . . . 2. Deﬁnitions and scope . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Baseline study and risk assessment . . . . . . . . . . . . . . . . . . . . 3.1. Risk assessment — connection with baseline study in the holism context 3.2. Baseline study — in the holism perspective . . . . . . . . . . . . . 3.3. Current and future legislation . . . . . . . . . . . . . . . . . . . 4. Concluding discussion . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ⁎ Corresponding author: Tel.: +44 7817139170. E-mail address: [email protected] (T.E. Butt). 1 Tel.: +44 7817139170. 0160-4120/$ – see front matter © 2013 Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.envint.2013.09.015 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 150 150 151 151 151 151 156 156 157 158 158 159 159 150 T.E. Butt et al. / Environment International 63 (2014) 149–162 1. Introduction 1.1. Background The main driver for improved and increasingly comprehensive environmental legislation in the UK and other European nations is undoubtedly European legislation (see Table 1). From the signing of the Treaty of Rome in 1957, until the signing of the Maastricht Treaty in 1992, the European Community was essentially an economic common market and had no mandate for environmental regulation. Any directive with an environmental element rested on the principles of either ‘public health protection’ or ‘harmonisation’ of environmental rules to avoid market distortion. The Maastricht Treaty ofﬁcially adopted the objective of sustainable development as community policy, advocating a high level of protection of the environment, based on the precautionary principles including the principle of “pollution prevention at source” and the “polluter pays principle” (Calleja et al., 2004; Luken, 2009; Pearce and Turner, 1992; Tadhg and Dermot, 2003). European waste and water management policies were originally developed to control pollution and protect the environment, which stimulated infrastructure investment in the waste and wastewater treatments sectors. Although criticised for its high cost, this succeeded in reducing concentrations of regulated point-source pollutants. It was however found that Member States were exploiting inconsistencies in the legislative text, and that standards set out in the Dangerous Substances Directive were not being achieved in many instances. Additionally, evidence of increasing pollution of waters (especially groundwater), and the recognition of the need to safeguard the ‘ecological quality’ of waters led to the revision and integration of the existing fragmented waste- and water-related legislation (listed in Table 1) into integrated management frameworks taking an ecosystem-based approach (Kallis and Buder, 2001). The Landﬁll Directive and the Water Framework Directive were published in the Ofﬁcial Journal of the European Community in 1999 and 2000, respectively. Both of these became European, and hence national law, in 2003. 1.2. Landﬁlls and risk assessment In order to protect public health and the environment, risk assessment has become a dominant public policy tool for making choices based on limited resources. Having realised the signiﬁcance and effectiveness of risk assessment in environmental management, environmental legislation has started to impose risk analysis as a tool for meeting legal requirements associated with waste hazards (Butt et al., 2009; Environment Agency, 2003a). For instance, to protect groundwater from landﬁll leachate contamination, risk assessment has been legislatively introduced into the UK since 1st May 1994, through “Regulation 15 of the Waste Management Licensing Regulations” (SI, 1994a) and the “Groundwater Regulations” (SI, 1998). The Landﬁll Directive is implemented in England and Wales through the “Landﬁll Regulations” (SI, 2002), made under the “Pollution Prevention and Control (PPC) Act” (England and Wales) 1999. The equivalent legislation, which is called Landﬁll (Scotland) Regulations, has come out in Scotland as well (SEPA, 2005a, 2005b; SSI, 2000, 2003). It can be inferred from the introduction of all these legislative instruments that the ‘out of sight, out of mind’ concept regarding wastes is no longer possible or permissible. To achieve the maximum protection of the environment against the hazards associated with landﬁll sites, all potential hazards must be identiﬁed and risks associated with them must be assessed. Landﬁll is the most widely employed method for disposal of waste around the world. The majority of municipal solid waste landﬁlls, including those that previously co-disposed hazardous materials, continue to receive a signiﬁcant proportion of bioreactive wastes which produce mainly greenhouse gases and wastewater known as leachate. Landﬁll leachate contains organic and inorganic pollutants including ammonia, heavy metals, humic-acids, persistent synthetic organic Table 1 Examples of some relevant legislation. 1. Waste Management Licensing Regulations (SI, 1994a, 2005): Under these regulations, waste management licences are issued by the Environment Agency to ensure that the authorized activities do not cause pollution to the environment, harm to human health or serious detriment to local amenities. 2. Groundwater Regulations (SI, 1998, 2009): This environmental legislation is an environmental protection measure which completes transposition of the Groundwater Directive (80/68/EEC) and provides enhanced protection for groundwater. 3. EU Directive on IPPC (Integrated Pollution Control and Prevention) (EU, 1996): This Directive (‘the IPPC Directive’) enforces a requirement for industrial and agricultural activities with a high pollution potential to have a permit which can only be issued if certain environmental conditions are met, so that the companies will bear the responsibility for preventing and reducing any pollution they may cause. 4. EC Directive on EIA (Environmental Impact Assessment) (EC, 1985): The Directive has been applied to the assessment of environmental effects of those public and private projects which are likely to have signiﬁcant effects on the environment. 5. Environmental Protection Act, 1990 and Environmental Act, 1995: The 1990 Act places certain obligations on businesses to ensure that their waste is suitably contained and disposed of in a proper manner. The 1995 Act covers a wide range of issues which are related directly and/or indirectly to the environment. This Act is to make provision with respect to contaminated land and abandoned mines; to make further provision in relation to National Parks; to make further provision for the control of pollution, the conservation of natural resources and the conservation or enhancement of the environment; to make provision for imposing obligations on certain persons in respect of certain products or materials; to make provision in relation to ﬁsheries; to make provision for certain enactments to bind the Crown; to make provision with respect to the application of certain enactments in relation to the Isles of Scilly; and for connected purposes. 6. Strategic Environmental Assessment (SEA) Directive (ODPM, 2003): The Directive ensures environmental effects to be taken into account by authorities during the preparation of plans and programmes in the ﬁelds of land-use, transport, waste and water management, energy, and a range of other sectors. Thus, this legislation enhances the degree of integration between various sectors rather than each sector being treated on its own as a separate entity. 7. EC Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora (The Habitats Directive) (EC, 1992): The EC Habitats Directive promotes the maintenance of biodiversity by requiring Member States to take measures to maintain or restore natural habitats and wild species at a favourable conservation status. The Directive introduces robust protection for those habitats and species that are of European importance. In applying these measures Member States are required to take account of economic, social and cultural requirements and regional and local characteristics. 8. Water Framework Directive — WFD (EC, 2000): The 1980 Groundwater Directive (80/68/EEC) aims to protect only groundwater whereas the WFD lead to a major overhaul of water protection legislation (Burges Salmon LLP, 2009). The WFD commits European Union member states to protecting and making all water bodies (rivers and lakes), transitional waters (estuaries), coastal waters and groundwater of good qualitative and quantitative status by 2015. Thus, this introduces integrated approach on much larger scale. 9. Landﬁll Directive (EC, 1999) and Landﬁll Regulations (Scottish Executive et al., 2005; SI, 2002): The overall aim of this environmental legislation is to prevent or reduce as far as possible negative effects on the environment, in particular the pollution of surface water, groundwater, soil and air, and on the global environment, including the greenhouse effect, as well as any resulting risk to human health, from the landﬁlling of waste, during the whole life-cycle of the landﬁll. This legislation also has important implications for waste handling and waste disposal. Principles of the Landﬁll Directive and WFD together aim for: • The minimum requirement of ‘no deterioration’ for all waters, • Achieving good ecological and chemical quality status for inland and coastal waters. Good ecological status can be deﬁned as only a slight departure from the biological community that would be expected in conditions of minimal anthropogenic impact. Good chemical status fulﬁls all the standards set by EU legislation for the concentration of chemicals in water. Additionally, more stringent requirements for ‘protected zones’ such as drinking waters, bathing waters, designated areas for the protection of habitats or species (including Natura 2000 sites), also other zones may be designated for the protection of economically signiﬁcant species or recreational activities. • Achieving international agreements such as OSPAR and eliminate emissions of priority hazardous substances, such as heavy metals and PAHs. T.E. Butt et al. / Environment International 63 (2014) 149–162 pollutants and inorganic salts of high concentration. If landﬁll leachate is not collected, treated and discharged safely, it shall become a potential pollution source which threatens soil, surface water and groundwater (Butt et al., 2009; Fatta et al., 1999). Therefore, landﬁll leachate is recognised as an important environmental problem and its risk assessment and management is thereby considered essential. Risk assessment, however, is a relatively new and fast developing science, both in terms of its adoption as a formalised analytical process applied to environmental issues, and also as a policy tool to assist regulators in the decision making process (Butt et al., 2009; Eduljee, 2000). This is not just in relation to landﬁll and other environmental sectors but also in relation to other areas including ecology, epidemiology, health and safety, radiation, earthquakes, ﬁnance, construction management, building contract selection, insurance, economics, ﬁre, landslides, ship navigation, the food industry, and the oil industry (Butt and Oduyemi, 2003; Butt et al., 2006, 2009; CIWEM, 1999). Regardless of the type of risk assessment needed and the speciﬁc environmental area of its application, a baseline study is the most important component of a risk analysis system (Asante-Duah, 1996; Blight and Fourie, 1998; CIRIA, 2001; Environment Agency, 2003a; ICE, 1994). In this paper it is this baseline study which is the core focus. 1.3. Research aims and methodology 1.3.1. Aims The main aim of the paper is to establish knowledge gaps in baseline study speciﬁcally regarding landﬁll leachate risk assessment, thereby paving a way for researchers to further research and develop in this particular area. Hence this paper identiﬁes and critiques the limitations of existing research literature in this area while simultaneously establishing the ‘state-of-the-art’ of baseline studies. Further aims in this work include developing some new insights in how to bridge the identiﬁed knowledge gaps, and the signiﬁcance of why these gaps need to be closed. However, as the focus of the paper is primarily to both review the existing ‘knowledge’ and ‘knowledge shortfalls’ regarding this subject matter, any new insights are only indicatively addressed for the sake of brevity, and in order to simply present a way forward for future research work in this area. 1.3.2. Methodology The basic methodology used to carry out this review study included the following elements: 1. The systematic selection of speciﬁc material used in the literature review process. 2. The criteria that are set and used to bench-mark the selected literature against. 3. A review of the relevant environmental legislation. Initially as a background to the review process, this paper sets the environmental legislative scene dating as far back as 1957. From that point onward, the paper describes how the environmental legislation came into being and has been steadily growing ever since then, both in terms of becoming more stringent and holistic. The paper next considers the links between the environmental legislation with risk assessment, and the signiﬁcance of baseline studies in risk assessments. In addition, the paper commences the review of literature from a broad prospective covering various business ﬁelds, both environment-related and non-environment-related (e.g. insurance and construction management sectors). Then the paper narrows the review down to contaminated land in which landﬁlls are deemed as a speciﬁc type of land contamination. After this, the paper then further narrows down the focus on to the main issue in this study which is landﬁll leachate. Following on from the above, a brief but clear list of a wide range of features that can make a baseline study more holistic are discussed (for a more integrated and uniﬁed risk assessment of landﬁll leachate). The 151 literature review work is then bench-marked against these features. It must be noted that this literature review considers not only recent studies but studies going as far back as the 1970s and 1980s. Thus the wide period considered under this study ensures that no appropriate studies, past or present, around the subject matter are missed out from the review process. Further, this paper does not consider one speciﬁc type of literature, but examines a diverse range of literature types including ones that cover the academic, public, private, consultancy, and industrial sectors respectively e.g. government documents (such as from the Environment Agency, SEPA, EPA US), as well as non-government documents, peer review academic research articles, reports, magazines, websites, and computer models. Some relevant case studies are also mentioned brieﬂy and in-line with the scope of the paper as explained later in Section 2.0. It is worth noting that as part of this review process, the guidance in the form of anecdotal conversations with professionals and academics in the ﬁeld was also used to ﬁnd more appropriate literature in this area. 2. Deﬁnitions and scope From the perspective of landﬁll risk analysis, the authors describe a baseline study process as that fundamental and initial stage of a risk assessment exercise of landﬁll leachate in which all basic information and/or data are collected, organised, and analysed. Speciﬁcally, in the case of landﬁlls, the baseline study needs to take account of a wide range of multi- and inter-disciplinary issues that the authors categorise into eight groups including: geology, hydrology, hydrogeology, topography, meteorology, geography, human inﬂuences, and site management. Some of these are partly mentioned in some literature (e.g. Environment Agency, 1999, 2003a; SEPA, 2003 – See Table 2 for more). Fig. 1 broadly exhibits the position of the baseline study and its eight groups in the spectrum of subsequent stages of risk assessment. Some examples on how various aspects of a holistic baseline study would link with various subsequent parts of landﬁll risk assessment are indicated in Section 3.2. It is emphasised that in this paper the term ‘baseline study’ is used (as a fundamental supporting mechanism in its own right for carrying out risk assessment), and this term should not be confused with the term ‘baseline risk assessment’. The paper regards baseline study speciﬁcally for landﬁll risk assessment and Fig. 1 is only to put the discussion of the paper in perspective. Therefore, implications and iterations of stages of risk assessment (along with that of baseline study) and other such details are not in the scope of the paper but for future research and development. Landﬁlling as a waste management option has potential to pollute all the three main natural factors of the environment which are land/soils, air, and waters. In scientiﬁc terms these are lithosphere, atmosphere, and hydrosphere, respectively (Butt et al., 2011). Unlike landﬁll gas and (more or less) degraded landﬁll waste, by virtue of its nature, landﬁll leachate speciﬁcally can pollute all of the three aforesaid principal factors. For instance, leachate vapours or fumes can ﬁnd their way into the ambient atmosphere in sufﬁcient amounts to present danger to human health and the environment, whereas these vapours or fumes can be containing chemical and/or biological hazards, volatile organics, etc. Moreover, landﬁll gas also breaks through from landﬁll leachate. Leachate can be an extremely powerful pollutant of water both above and below ground level – hydrosphere and hydrogeosphere. In addition, leachate contaminants can pollute land/soils as it moves through the ground either mixed with water or on its own (e.g. through the unsaturated zone under a landﬁll). Therefore, in general, landﬁll leachate can be seen as a lot more hazardous product of a given landﬁll than the other two – landﬁll gas and (more or less degraded) landﬁll waste. Since landﬁll leachate generally presents a lot more substantial environmental threat as well as given the limitation on time, resources, and the scale of the work undertaken, this must be noted that main scope of this research study is only landﬁll leachate not landﬁll gas or landﬁll 152 T.E. Butt et al. / Environment International 63 (2014) 149–162 Table 2 Literature review examples/case studies: discussing elements of baseline study present and absent. Note: The term ‘elements absent’ implies knowledge gaps and limitations of the research works carried out and reported to date. Publication Elements present Elements absent Golder Associates, 2002 This publication regards risk assessment only for small and closed landﬁlls. It brieﬂy mentions hazards and risks in the context of contamination of groundwater; contamination of surface water; gas accumulation; and direct exposure to contaminated soil, sharp objects, or hazardous gases. These are the only four scenarios, which this publication addresses very brieﬂy. Environment Agency, 2007 This guidance, which is one of the most relevant guidance documents for landﬁlls, addresses the landﬁll sector in a very broad sense. It includes a number of very relevant aspects that can help risk assessment and baseline study exercises for a given landﬁll e.g. site investigation, groundwater protection and hydrogeology, closure and after closure, landﬁll engineering, etc. Environment Agency, 2012 This website of the Environment Agency lists down a diverse range of guidance documents relevant to all sectors regulated under EPR (Environmental Protection Regulations) which also includes the landﬁll sector. From the risk assessment perspective, the most relevant guidance is Environmental Risks Assessment, abbreviated as H1 in the list. The purpose of the H1 is to assist risk assessors in explaining and justifying choice of risk control measures (Environment Agency, 2011a). This document has a number of annexes and sub-annexes around various relevant aspects such as landﬁll itself (Environment Agency, 2011b), groundwater protection (Environment Agency, 2011c), hydrogeological risk assessments for landﬁlls (Environment Agency, 2010), etc. Unlike the Environment Agency's website of 2012 which is for various sectors, this website of the Agency is speciﬁcally for the landﬁll sector. Hence this website contains technical guidance to help readers to understand the standards that the Agency wants the landﬁll sector to achieve when designing and managing a landﬁll site. It covers diverse landﬁll related subjects such as waste acceptance; monitoring of landﬁll leachate, groundwater and surface water; landﬁll gas; landﬁll engineering; landﬁll permitting and surrender. This book provides scientiﬁc and technical recommendations to address challenges that risk assessment procedures faces e.g. lengthy delays in making complex decisions; lack of data leading to signiﬁcant uncertainty in risk assessment; etc. The book embeds various risk assessment concepts within a broader framework for risk-based decision-making. This Environment Agency document provides guidelines for risk assessment of landﬁll leachate. Hazards are considered from the perceptive of groundwater as a receptor/target. Some baseline study modules such as geology and hydrogeology are brieﬂy addressed. The SEPA document, on the other hand, in addition to these elements, also brieﬂy touches upon aspects such as maximum, minimum and most likely values of various parameters such as leachate quality. However, as the title of the SEPA document states, the main focus of this guidance note is not risk assessment of landﬁll leachates but the monitoring aspects of landﬁll leachates, ground waters and surface waters alike. This publication is only for closed landﬁll sites. Both hazard and risk are together divided into three types namely, physical, chemical/bio-chemical and physico-chemical. Thus, no differentiation is made between hazard and risk when using the above categorisation. A few aspects of some risk analysis modules (such as hazard identiﬁcation, concentration assessment, exposure analysis) are addressed to a limited extent. This website of the EPA (Environmental Protection Agency) lists down a diverse range of guidance documents relevant to various types and aspects of risk assessment such as: exposure factors (EPA, 2011); toxic release inventory (TRI) (EPA, 2010); evaluation of toxicity of chemicals (EPA, 2009a); development, This publication is not for presenting a detailed algorithmic, ready-to-use, sequentially linked, categorical, user-friendly formatted, continual and step-by-step baseline study system, which a risk assessor could follow from the start to ﬁnish in a self-guided fashion in order to identify and categorise all landﬁll-site characteristics that are needed in different follow-on stages of a risk assessment for landﬁll leachate. All the baseline study elements described in Section 3.2 are fully or partly absent. The scope of the guidance document does not include presentation of a holistic baseline study system which a risk assessors could use as a ‘one-stop-shop’ for a given landﬁll leachate's risk assessment. A range of the baseline study parameters indicated in the 9 elements given in Section 3.2 (e.g. how to employ statistical considerations to establish worst-case and most likely scenarios, uncertainty assessment, etc.) are not included. Moreover, the parameters which have been included are not laid out in a categorical and sequential manner so that they could be readily used by risk assessors using a ‘step-by-step’ approach. Same as the case of Environment Agency, 2007 (see above). Environment Agency, 2011d EPA, 2009d Environment Agency, 2003a and SEPA, 2003 CIRIA, 2001 EPA, 2012 Some of various guidance notes on the website address some aspects which can become part of baseline study for landﬁll risk assessment. However, none of the guidance documents offer a holistic baseline study system which risk assessors could use as a ‘one-stop-shop’ in a sequential, categorical and step-by-step manner. Since the book addresses risk assessment in a broader context, it is not speciﬁcally for risk analysis of landﬁlls and therefore does not address the issue of holistic baseline study for risk assessment of landﬁll leachate, and therefore does not cover the diverse parameters indicated in Section 3.2 of the paper. Apart from some aspects of the baseline study modules brieﬂy addressed (as mentioned in the left column), overall all the elements from 1 to 9 in Section 3.2 are either absent or not addressed sufﬁciently to a level where they all could be tied together into an algorithmic procedure of a quantitative baseline study system. In-operation and pre-operation landﬁlls are excluded. The publication is not speciﬁcally for landﬁll leachate. Though some aspects of risk analysis modules (mentioned in the left column) are taken into account, the baseline study work is almost totally missed out for the elements indicated above in 1 to 9 in Section 3.2. None of the guidance documents are speciﬁcally for risk assessment of landﬁll leachate using a holistic baseline study approach, with all the 9 elements listed in Section 3.2 integrated into it. T.E. Butt et al. / Environment International 63 (2014) 149–162 153 Table 2 (continued) Publication Elements present EPA, 2012 evaluation and application of environmental models (EPA, 2009b); dosimetry-based cumulative risk assessment (EPA, 2009c); cumulative health risk assessment of multiple chemicals, exposures and effects (EPA, 2008); and assessment of risks from metals (EPA, 2007). This publication provides guidelines for characterisation of municipal solid waste in Portugal. This can be helpful as a part of baseline study in the Site Management unit (Section 3.2) where ‘waste types’ is one of the parameters. This publication is for risk assessment of landﬁll gas only. It touches on a range of risk assessment modules such as gas generation, human exposure, etc. This publication, which is a research paper, is related to risk analysis for landﬁll gas sites. It includes modules such as exposure assessment, toxicity assessment and risk estimation. This document provides generic material for the development of functional risk assessment guidance to assist in issues like contaminated land, waste management, and major accident hazards (DEFRA, 2002). It examines a range of risk assessment topics such as dealing with uncertainty, types of quantiﬁcation, and evaluation of the signiﬁcance of a risk. This guidance is a useful starting point. It serves as the ‘ﬁrst port of call’ for many Environment Agency ofﬁcers, before they tackle the detailed project work. It can also be used by anyone else interested in risk-based decision-making in Government. (DEFRA, 2002). This landﬁll risk assessment publication is from the perspective of issues such as noise, odour, litter, birds, vermin, insects, and mud on road. This publication focuses on landﬁll gas, not leachate. Martinho et al., 2008 Gregory et al., 1999 Redfearn et al., 2000 DETR et al., 2000 Environment Agency, 2003b Environment Agency, 2003c Harris, 1984; Asante-Duah, 1990; DOE, 1994a; Jones, 1997; EPA, 2003; Google, 2006; Arell and Folkes, 2004. Bernard et al., 1996, 1997 Bardos et al., 2003a, 2003b; SCEG, 2003; Nathanail and Nathanail, 2003 Environment Agency, 2004 These publications are on a Hazard Ranking System (HRS) employing a scoring mechanism, which is a semi-quantitative approach i.e. neither purely quantitative nor entirely qualitative (Chapman and Wellington, 2004; EPD, 2004; Lloyd and Wilson, 2002; Pollard et al., 1995; Robinson, 1999). HRS is a principal mechanism that the EPA (US) uses to place uncontrolled waste sites on the National Priorities List (NPL). It is a numerically based screening system that uses information from initial, limited investigations – the preliminary assessment and site inspection – to assess the relative potential of sites to pose a threat to human health or the environment. These two papers (Part 1 and 2) are on hazard analysis of landﬁll leachate. They discuss leachates from 25 landﬁll sites in France as case studies, with a number of methods of determining leachate toxicity. They then compare the physico-chemical characteristics of leachates. These four articles draw on some aspects of hazard assessment and risk analysis from the perspective of contaminated land. This document brieﬂy addresses a broad and diverse range of facets of landﬁll risk analysis along social, technical, environmental, economic, legislative and managerial themes. Both landﬁll gas and leachate are addressed. The main scope of the guidance is limited to ﬁve areas of risk assessment, which are accidents and their consequences; hydrogeology; landﬁll gas; particulate matter; and stability. Blight and Fourie, 1998 This is only for landﬁlls. Pollard et al., 2000 This document provides technical guidance to Environment Agency staff and to applicants on the practical environmental risk assessment tools that can be used in the waste management licencing process to assist in the design and operation of a site. However, it needs to be used alongside the DETR/EA Guidelines for environmental risk assessment and management (DETR et al., 2000). Elements absent This guidance document does not consider all the other elements and parameters of the baseline study as indicated in Section 3.2 Landﬁll leachate is not included in this publication. Thus, the elements from 1 to 9 (listed in Section 3.2) are completely absent from the landﬁll leachate perspective. A detailed baseline study is not within the scope of this publication. All the elements from 1 to 9 (Section 3.2) are absent in the context of landﬁll leachate. This publication addresses a range of risk analysis issues in general (listed in the left column). However, the focus of this work is not speciﬁcally on landﬁll leachate, but rather on a host of environmental hazard issues. Therefore, it is too generic to be of speciﬁc use. Moreover, the document does not address the baseline study factors indicated in points 1 to 8 of Section 3.2 which are strictly related to landﬁll leachate. The publication is not about landﬁll leachate in the ﬁrst place. The elements 1 to 9 are totally absent. Even for landﬁll gas issue, the baseline study elements 1 to 9 (Section 3.2) are not addressed in an integrated manner. The HRS does not offer a holistic baseline study methodology for landﬁll leachate. Also speciﬁcally from the perspective of landﬁll leachate, the elements from 1 to 9 mentioned in Section 3.2 are absent in the HRS approach. These publications do not present a strategic baseline study framework comprising the 9 elements (depicted in Section 3.2) for landﬁll leachate. These articles do not speciﬁcally address the baseline study of landﬁll risk assessments and all the 9 elements (Section 3.2) are absent from the perspective of landﬁll leachate. As the document states itself that there are ﬁve main areas, which constitute the main scope of the guidance (listed in the left column). Yet landﬁll leachate is not one of them, though is addressed to a limited extent. The guidance also mentions that it does not provide all the detail needed to conduct risk analysis for a landﬁll site. Although some baseline study modules such as hydrogeology are included while others like meteorology, human inﬂuence and geography are not addressed. Overall, a holistic baseline study is not in the scope of this publication. This study very brieﬂy outlines the requirements when carrying out a baseline study. However, there is no evidence of a strategic and systematic methodology for a baseline study encapsulating all the elements indicated and described in Section 3.2. Although, this document introduces the concept and stages of environmental risk assessment, it does not offer a holistic baseline study methodology speciﬁcally for landﬁll leachate systems. (continued on next page) 154 T.E. Butt et al. / Environment International 63 (2014) 149–162 Table 2 (continued) Publication Elements present Elements absent EPD, 1997 This publication is a guideline for hazard analysis of landﬁll gas. It brieﬂy covers various aspects of hazard and risk assessment such as hazard mitigation measures and the source-pathway-target analysis approach. ICRP, 1975; ICRCL, 1987; Eisenbeis et al., 1986; OSHA, 1989; Johannsen, 1990; Montague, 1991; Kavazanjian et al., 1995; Jaggy, 1996; Asante-Duah, 1996; ICE, 1994; WDA, 1994; Pieper et al., 1997; Senior, 1995; DoE, 1986, 1991, 1993, 1995a; CIRIA, 1993, 1995. Some old literature (with examples given in the left column) regarding landﬁll assessment, in particular, and other risk assessment procedures, in general, were also extensively studied to ensure that no historical work was carried out in the area of the development of a holistic framework for baseline study and risk analysis. The literature was found to address various risk assessment issues like seismic hazard analysis for landﬁlls; carcinogenic and non-carcinogenic risks; air contamination; landﬁlls' leakage; exposure assessment; baseline study; toxicity assessment; risk estimation; speciﬁc landﬁll types and nature; radiation; contaminated land remediation; speciﬁc hazards such as polychlorinated dibenzo-p-dioxins and furans (PCDD/F); landﬁll microbiology; landﬁll gas; landﬁll completion; landﬁll design and construction aspects. This publication relates to exposure assessment for humans from contaminated lands. Details on various aspects of exposure assessment are given. Examples include exposure parameters (such as exposure duration, frequency), soil release and transfer mechanisms, exposure equations, human activities and ages, exposure routes, and various land-uses. These publications are speciﬁcally for landﬁll leachate and focuses on the exposure assessment and hazards' concentration assessment sections of a total risk assessment system respectively. An integrated and quantitative model of exposure analysis is presented and some links are also drawn with the relevant parts of a baseline study. The study focuses on one type of hazard i.e. particulate matter (PM) and only in air as an exposure medium. The only exposure route accounted for is inhalation, and this work only considers humans as receptors. This document can contribute to a landﬁll risk assessment in terms of exposure analysis. This publication portrays exposure assessment in a more complete manner than any other literature studied to date. The focus is not on environmental receptors but on only human health. Similarly, not all potential exposure pathways have been included, but only the six which cover most risk to human health from landﬁlls. A procedure on exposure assessment has been outlined and only humans have been considered as receptors. This study only addresses the exposure analysis aspects, and of that, only the chemicals issues. The publication is not for landﬁll leachate. Even for landﬁll gas, the elements from 1 to 9 (Section 3.2) are either completely absent or are only covered in a cursory manner (as described in the left column). However, from the speciﬁc leachate point of view, all the 9 elements are totally absent. None of these publications (including the ones which are speciﬁcally for landﬁlls) offer a categorical and sequential procedure for the baseline study of landﬁll leachate in a holistic manner. For instance, ICE's work of 1994, even though it touches upon a baseline study to a degree, but focuses instead on contaminated land rather than speciﬁcally on landﬁll leachate. Similarly, Asante-Duah (1996) describes all the important aspects of risk analysis including baseline study but not in the form of an integrated methodology. His work is rather an independent analysis of each in different individual chapters. In summary, all the elements from 1 to 9 (listed in Section 3.2), have not been tied together in an algorithmic format either for landﬁll leachate or for that matter in regard to any other environmental issue. As the title of the publication states that the focus of the publication is exposure analyses, thus a baseline study has not been addressed as such. Moreover, it is for contaminated land in general and not landﬁll leachate speciﬁcally. DEFRA and Environment Agency, 2002 Butt et al., 2011; Butt and Oduyemi, 2003 Moschandreas et al., 2002 DoE, 1995b Eduljee, 1998 Daugherty, 1998 EPA, 1992, 1999 SEPA, 2002 These publications purely consider exposure assessment. However they cover the subject from many different perspectives including types of hazards, pathways, receptors and exposure; also, types of dose, (e.g. potential dose, intake dose, applied dose, etc.), exposure dose relationships, uncertainty assessment, individual and population exposure, exposure analysis in epidemiological studies, and the position of the exposure assessment itself with respect to risk characterisation. This publication regards landﬁll risk assessment in the context of landﬁll leachate liners and drainage systems. CPPD, 2004 This publication is in draft form only. It regards hazard and risk assessment in the context of natural hazards such as ﬂooding, earthquakes, landslides, and wildﬁres. Rudland et al., 2001 This work describes a basic framework for risk analyses of contaminated land. Auckland Regional Council, 2002 This publication, which is a government document for local authorities, covers risk assessment in a very broad sense when regarding hazard. These include natural hazard such as tornadoes, ﬂooding, earthquakes; technological hazard like high pressure gas mains The baseline study system is not within the scope of the publication. Thus, all the 9 elements (Section 3.2) are absent. The publication does not present baseline study procedures. This publication is not speciﬁcally for landﬁlls. This publication does not offer a holistic baseline study for landﬁll leachate that could readily be used in conjunction with a landﬁll risk assessment process. In summary, all the elements above from 1 to 9 are absent. Same comments as DoE, 1995b above. This study is not speciﬁcally for landﬁlls, and therefore there is no holistic baseline study procedure covered in the publication, even if only the chemicals issues are considered. These documents do not portray a holistic procedure for carrying out baseline study either speciﬁcally for landﬁlls or for any other environmental risk analysis scenario. When considering the landﬁll perspective All the 9 elements (in Section 3.2) are absent in these publications. Apart from the aspect of liners and drainage systems, which can form part of a site management module of a baseline study, the elements from 1 to 9 (in Section 3.2) are not fully present. The publication is not for anthropogenic activities, and therefore does not consider landﬁlls. The document only discusses various natural hazards and provides statistics on them, but does not present a structured baseline study procedure even for these natural hazards listed in the adjacent column. This work is not speciﬁcally for landﬁlls. Hence all the elements from 1 to 9 (in Section 3.2) are absent in the context of landﬁll leachate. This publication is not speciﬁcally for landﬁlls. It just encapsulates all natural as well as anthropogenic hazards without presenting a holistic baseline study procedure. The format is more like a checklist. Thus, the entire baseline study elements from 1 to 9 (considered in Section3.2) T.E. Butt et al. / Environment International 63 (2014) 149–162 155 Table 2 (continued) Publication Elements present Auckland Regional Council, 2002 failure, or computer systems failure; biological hazard including disease among people, animals or plants; and civil/political hazard comprising terrorism activities and civil unrest. The focus of this work is landﬁll gas and also that of a speciﬁc landﬁll site. Scott Wilson (Hong Kong) Ltd. (1997) Environment Agency, 1997 DOE, 1998 EPA, 1988, 1996a, 1996b, 1996c, 1998 This document addresses risk assessment from the perspective of human health only as a receptor, and only for those landﬁlls which have as a pollutant source contaminates from house hold waste. This environmental guidance document mentions Risk-Based Corrective Action (RBCA) standards that were developed for addressing petroleum and chemical release. The purpose of this guide is to explain risk-based decision making and the RBCA process for environmental restoration of chemically contaminated sites. The ﬁrst four documents consider risk assessment of neurotoxicity, reproductive toxicity, ecology and carcinogens respectively. The ﬁfth publication is on the evaluation of the potential carcinogenicity of Acrylonitrile. Government of Western Australia, 2009 This report is speciﬁcally on the baseline study of contaminants in groundwater carried out speciﬁcally for disused waste disposal sites in the Swan Canning catchment area in Australia. Hokkanen and Salminen, 1997 This research work addresses a broad range of waste management options including landﬁlls, composting, incineration, and transport issues. The main theme of the paper is waste production, recycling and disposal. This paper discusses various risk assessment tools and how to select a speciﬁc tool for a speciﬁc scenario based on the following: (i) the appropriate tool by reference to the type of risk problem under study; and (ii) the appropriate level of sophistication selected as needs, complexities, priorities and data allowance. This paper addresses a range of waste management options including landﬁlls, incineration, compost and sewage. The focus of this publication is the characterisation of waste from different perspectives such as recycling. Chowdhury, 2009 Pollard et al., 2006 Giusti, 2009 Loughborough University, 2006 Villanueva et al., 2009 This paper considers a process-based waste management system and uses a Parisian case study. CMSA, 2004; Puncochar, 2003; Koivisto et al., 2001; Feldman and White, 1996; CHEM Unit, 2003; Pauluhn, 1999; PDC, 2003; Thatcher, 2002; EPA, 2002; Hull et al., 2002; HCPC, 2004; Catlin et al., 2001; Hoffman et al., 2003; Kinsman and Maddison, 2001; Hekster and de Voogt, 2002; DOE, 1993, 1994b; Brown, 2000; Norton, 2002; QUT, 2004; Keith et al., 1999; Tarazona, et al., 2000; Fleming and Fleming, 2002; A-NPDC, 2004; Anderson and Albert, 1999; Jones et al., 2004; Karvonen, 2000; Brown and Stringer, 2002; Ochola et al., 2002; DEM, 2004; Sanchez and Burger, 1998; UCL, 2002; Gillanders, 2003; Crawford-Brown and Brown, 1997; Chen et al., 1998; HSE, 1998; Pease, 1992; Muth et al., 2001; Tarazona and Vega, 2002; DHS et al., 2009; Wessberg et al., 2008; Pollard et al., 2004; EPA, 2000b; McKenna, 1998 These publications focus on hazard and risk assessment for when considering the following subjects: mining, the workplace, genetically modiﬁed organisms, neurology, the indoor environment, ecology, toxicology, software systems, wildlife, terrorism and safety issues, human health and epidemiology, aquatic chemistry and aquatic toxicology, seismology, natural hazards (like drought, wildﬁres/forest ﬁres, storms, etc.), explosions, ecotoxicology, ﬁres in agrochemical warehouses, aquatic environments, human health, contaminated land, food safety, health and safety systems, radiation, terrestrial environments, energy and electricity, shore environments, air quality, cattle importation, the economy, microbiology, farming machinery, nuclear production sites, educational establishments, project management systems, carcinogenicity, petroleum contamination, offshore installations and the oil industry, regulations development, food issues, chemicals and eco-systems, information technology, accidental emissions, water utilities, chemical mixtures, and hormesis. Elements absent are absent not only for landﬁll sites but also when considering any general hazards. This study does not offer a baseline study system comprising features 1 to 9 (in Section 3.2) for landﬁll leachate, and in a similar manner not even for landﬁll gas production. This work does not present a baseline study methodology encompassing the aspects listed in Section 3.2 for landﬁll leachate. The purpose of this document is not to present a strategic and integrated baseline study framework, and speciﬁcally does not consider landﬁll leachate. The system described is more over only used to determine the data requirements needed for technical decision making, rather than focusing on the speciﬁc process steps needed for a risk analysis, or when conducting a baseline study. These documents may indirectly be useful in risk analysis of landﬁll leachate in the context of establishing neurotoxicity, reproductive toxicity, ecological and carcinogenic affects of leachate pollutants. However, these publications are not produced from the point of view of landﬁll leachate and thus, in this sense all the baseline study elements from 1 to 9 (in Section 3.2) are absent. As already mentioned in the adjacent column, this document only considers a speciﬁc case, and therefore does not present a holistic baseline study system (with the 9 elements given in Section 3.2) that could be readily useable for other landﬁll scenarios. This publication does not consider the holistic baseline study systems speciﬁc to landﬁll leachate. This paper does not cover risk assessment or the baseline study part of risk analysis. The scope of this paper does not cover the presentation of a holistic baseline study framework speciﬁc to landﬁll leachate. This paper is not meant for the development of a baseline study methodology that could constitute a risk assessment system speciﬁc to landﬁll leachate. This publication is not for risk assessment of landﬁll leachate, and thus there is no description of a baseline study framework for risk assessment speciﬁc to landﬁll leachate. The scope of this paper does not address a baseline study procedure connected to a risk assessment of landﬁll leachate. Thus, the publication does not contain a holistic baseline study framework, and all the elements listed in Section 3.2 are absent. These publications address the risk assessment context in a diverse range of ﬁelds and they all need a holistic baseline study system speciﬁc to each area. However, none of these publications are useful for landﬁll sites. 156 T.E. Butt et al. / Environment International 63 (2014) 149–162 Risk Assessment / Analysis Baseline Study Geology Hazard Identification Hydrology Exposure Assessment Hydrogeology Concentration Assessment Migration Assessment Topography Significance Assessment Meteorology Uncertainty Assessment Geography Hazard Indices Risk Quantification Human influences Site management Fig. 1. The baseline study modules and its position in relation to overall risk assessment structure (adapted, derived and concluded from the work of various authors including CIRIA, 2001; CMSA, 2004; Environment Agency, 2003a; EPA, 2000a; Peacock and Whyte, 1992; TOSC, 2000; Viswanathan et al., 2002; WDA, 1994). waste. A cut off had to be drawn to deﬁne the manageable size of the study and the word ‘holistic’ is used speciﬁcally within this scope which is landﬁll leachate. Therefore, it is worth mentioning that the term ‘holistic’ in this paper implies an overall framework with a wholesystem and uniﬁed approach (Arquette et al., 2002; Aven and Kristensen, 2005) that covers all aspects and factors of the baseline study (See Section 3.2) from the start to end in the context of landﬁll leachate only – neither landﬁll gas nor (more or less) degraded landﬁll waste, as the inclusion of these two would have grown the paper beyond limits and the depth of study speciﬁcally around landﬁll leachate alone was going to be compromised. The term ‘holistic’ not only means ‘inclusiveness’ and ‘comprehensiveness’ but also implies ‘appropriate integration’ of and ‘linking’ between these aspects and factors (Section 3.2) in an algorithmic, coherent, consistent, and sequential manner so that these could logically and systematically be referred to in the later stages of a risk assessment process. This is in line with the general principle of ‘holism’ or ‘wholism’ as concisely summarized by Aristotle in the Metaphysics: “The whole is more than the sum of its parts” – where the word holistic or holism comes from a Greek word ‘holos’ which means ‘all’, ‘entire’ or ‘total’ (Ask Deﬁne, 2013; Environment, 2013; Philosophy Basics, 2013; Sobel, 2010). The idea is that all properties of (a baseline study) system cannot be determined or explained by its component and sub-component parts alone (Section 3.2). Instead, the system as a whole determines an important way of how the parts behave and can be effectively and efﬁciently used in the subsequent stages of a risk assessment exercise of landﬁll leachate. This is the context in which the term holistic or holism has been deployed in the paper. Furthermore, in order to establish what crucial parts a holistic baseline study system (speciﬁcally for landﬁll leachate) is supposed to be composed of, not only ‘holism’ theme but the ‘reductionism’ theme has also been employed (Environment, 2013). In other words, ‘synthesis’ and ‘analysis’ have been used in the study. 3. Baseline study and risk assessment 3.1. Risk assessment — connection with baseline study in the holism context The review of environment-related literature clearly shows that a baseline study is a crucial and primary factor in an environmental risk analysis. Moreover, the investigation (contained Table 2) led to the conclusion that a comprehensive, robust, detailed, and sound risk assessment methodology, incorporating a number of essential features (including that of baseline study) does not exist in an integrated manner. Examples of essential features are: • Encompassing various types of landﬁll systems and their surroundings (hydrosphere, atmosphere, geosphere, and any combination of these e.g. hydrogeosphere); • Taking into account all possible characteristics of landﬁlls in terms of risks and quantiﬁcation of risks posed by landﬁlls including statistical descriptions such as maximum minimum, and most likely values; • Encapsulating other features and scenarios that render a risk analysis more comprehensive such as uncertainty assessment and signiﬁcance assessment; and • Embedding procedures of relevant individual modules (such as hazard identiﬁcation, hazard concentration assessment, exposure analysis and quantiﬁcation, pollutants migration, and baseline study). Inconsistency in risk assessments is an important issue, not only for the government sector (e.g. the Environment Agency and SEPA – who are environmental regulators) but also the commercial sector including environmental (risk) consultants and the landﬁll industry – who have to produce site-speciﬁc risk assessment reports for environmental regulators (Booth and Jacobson, 1992; Buss et al., 2004; Environment Agency, 2007; SEPA, 2011). Irrespective of quality of site-speciﬁc data and variation in style and expertise of regulators and consultants, one of the most signiﬁcant reasons of inconsistency is no two landﬁll scenarios are the same. Characteristics of landﬁll scenarios may vary widely from one to another, not only in terms of a landﬁll itself and its management practices but also the setting around it e.g. diversity of receptors, and pathways. Therefore, a holistic risk assessment system is required which encapsulates all possible characteristics, features, aspects and factors in one place – under one ‘umbrella’ – in which risk assessors could use to appropriately choose from and even be able to explain what has not been included and why. This is not to be merely a check list of items but also a complete set of guiding principles of how, when, where and why various items of risk assessment interact with each other and what needs to be included (or even excluded) with justiﬁcations for a given risk assessment scenario. To help solve the issue of inconsistency and lack of holism in risk assessments, a holistic baseline study can be effectively useful. In other words, a consistent and coherent baseline study system is one of the crucial requirements to generate consistent and coherent risk assessments. This is explained further in Section 3.2. Since inconsistency among risk assessments also leads to compromise the degree of risk comparisons, therefore, consistency in risk assessments can help the issue of risk comparisons between two or more landﬁll scenarios in a number of ways e.g. where a new landﬁll can more safely be sited. Thus, a consistent baseline study system can also be useful in this regard. Furthermore, landﬁll leachate is a multi-dimensional pollutant source that can (either directly or indirectly) pollute lithosphere, atmosphere, hydrosphere, and even any combination of these (details in Section 2.0, paragraph 2). As individuals, these three entities are not only fundamental constituents of the environment but also principal media of transmission of contaminants. Therefore a more comprehensive, concise, and robust risk analysis system, underpinned by a correspondingly more strategic baseline study system, will be needed. Furthermore, the environment legislation has also been growing stringent as well as holistic (as explained in Section 3.3 and Table 1) which is requiring risk assessments to be increasingly integrated and uniﬁed. Therefore, in order to render a risk assessment holistic, a correspondingly holistic baseline study system will be required for a baseline study lays bases of subsequent stages of a risk assessment in a given scenario (see Fig. 1 which is an indicative of risk analysis steps). If the T.E. Butt et al. / Environment International 63 (2014) 149–162 baseline study system is not lacking holism and is uniﬁed, consistent, and integrated, then so will more likely be the risk assessment which is primarily based on the good and appropriate quality of the baseline study – the foundation. However, the main focus of this study is the baseline study itself as a system and not the risk assessment as such, therefore the following section purely addresses the baseline study and in more detail. 3.2. Baseline study — in the holism perspective A comprehensive review of risk assessments currently used for environmental management highlights clearly that there is currently a lack of an integrated procedure for carrying out baseline study in various environmental ﬁelds, and especially in landﬁll leachate management. Although a great deal of research on risk-based approach in a number of environmental ﬁelds (including landﬁll waste management) has been carried out (See Table 2), none of the studies appear to have addressed speciﬁcally landﬁll leachate via developing a holistic baseline study system. In order to support risk assessments speciﬁcally in relation to landﬁll leachate, a list of a number of elements or features are indicated below that need to be drawn together in a sequential and algorithmic manner to form a holistic – a consistent, coherent, and yet wholesystem – architecture of baseline study. However, details on how these elements should be assembled together to construct the holistic baseline study's architecture are not within the scope of this study. Based on extensive literature review, the study is to identify what knowledge gaps exist in the state-of-the-art of baseline study, and only indicatively mention why and how these gaps can be bridged. Where appropriate, the paper still points out relationships of the below-listed elements of the baseline study system not only among themselves but also with the other parts of risk assessment, and an indicative framework of a holistic baseline study is shown in Fig. 1. An exhaustive study of literature is contained in Table 2, which establishes that these below-listed elements are either entirely or partly absent in current approaches and practices: 1. Keeping in view the multi- and inter-disciplinary nature of a baseline study for landﬁll leachate, the authors divide it into eight modules that are listed below with examples of parameters which these modules can take into account. Current baseline study approaches for risk assessments are found not to have included all of these eight aspects in an integrated manner. i. Geology: top soil, drift, rock, porosity, effective porosity, ﬁssures, density, geological materials and minerals, depth and width or volume of the geological materials, and other geological properties. ii. Hydrology: evaporation, transpiration, interception, surface runoff, inﬁltration, percolation, and groundwater ingress. iii. Hydrogeology: vadose and phreatic (also called unsaturated and saturated) zones, perched groundwater, hydraulic gradient, permeability, groundwater speed and direction, and other hydrogeological properties. iv. Topography: landforms and inclinations (to assist in measuring runoff to or from a given landﬁll), natural environment, habitats, built environment, water-courses, etc. v. Geography: latitudes, longitudes, geographic zones (e.g. tropical and other geographic properties that can also help in estimating other baseline study parameters such as expected rainfall). vi. Meteorology: precipitation (duration, frequency, intensity), wind speed and direction, wet and dry bulb temperatures, humidity, and degree of sunniness and cloudiness. Factors like wind, temperature, and humidity can also help with establishing degree of formation of leachate vapours or fumes. vii. Human inﬂuences: past, present, or future potential anthropogenic activities (like quarrying, water abstraction, construction, and development). 157 viii. Site management: site history, site type, site location, site design and engineering (e.g. liners, drainage system), site surface area, waste management activities, waste types, environmental monitoring, leachate collection system, leachate management practices. 2. The authors do not ﬁnd evidence of a detailed, algorithmic, readyto-use, sequentially-linked, categorical, user-friendly-formatted, continual, and step-by-step baseline study system, which a risk assessor could follow from start to end in a self-guided fashion to identify and categorise all landﬁll site characteristics that are needed in different subsequent stages of a risk assessment process for landﬁll leachate. 3. There is a lack of ‘signiﬁcance assessment’ of all baseline study parameters and their characteristics. For instance, what conservative measures are taken – and for which parameters and why? Is the amount of interception for a given landﬁll signiﬁcant enough to consider in leachate quantity measurement? Is the quantity of liquid waste small enough to be ignored in the water budget equation of the landﬁll on annual basis? Etc. 4. There is a deﬁciency of ‘uncertainty assessment’ of all baseline study parameters and their characteristics, where these uncertainties could be due to estimation methods, lack of knowledge, data quality, etc. 5. No appropriate consideration has been given to the format and means of data collation at baseline study stage that could assist in working out worst-case and most-likely risk scenarios in subsequent stages of a risk assessment process. Such means are indicated in points 6, 7, and 8 below: 6. Employment of statistical descriptions lacks particularly in the context of maximum, minimum, and most-likely values of various parameters (e.g. evapotranspiration, precipitation, interception, and groundwater ingress). Such statistical descriptions can be helpful to ﬁgure out worst-case and most-likely risk scenarios; as well as to address uncertainties, and temporal and spatial variations. 7. There seems to be a deﬁciency of appropriate consideration of temporal and spatial variations of various parameters of the baseline study. For instance, temporal variation of leachate quality in terms of its becoming mature over time; spatial variation of the unsaturated zone underneath a given landﬁll in order to ﬁgure out effective vadose thickness; etc. 8. For risk assessment to be quantitative, all appropriate parameters of the baseline study need to be quantiﬁed. Examples of such parameters are interception, precipitation, and groundwater ingress. The more the objective measurement of such parameters is, the more successful the quantiﬁcation of the associated risks will be. 9. A given landﬁll can be at pre-operation stage (i.e. planning, design, and development phase), in-operation stage, and/or post-operation stage (i.e. completed and post closure phase). In the current baseline study approaches, there is a lack of consideration of the issues regarding the three landﬁll stages taken together. In order to integrate all these elements there is a need for a comprehensive, algorithmic, and systematic baseline study framework which could provide guidelines on acquiring, sorting, and analysing all the data and/or information of preliminary investigation of a given landﬁll in such a useful format which could be systematically related to the subsequent stages of the risk analysis. A number of case studies have also been considered as a part of the literature review. No case of landﬁll risk assessment was found to have considered a baseline study in a holistic and integrated manner with all the elements described above. It has been noticed that only a few of the aforesaid aspects of the baseline study are variably taken into account. For instance, groundwater, rainfall and locations of nearby surface water courses were among the main parts of the baseline study carried out in the assessment of contamination of the Swan Canning River system by landﬁll leachate (SRT, 2009). But the baseline study process 158 T.E. Butt et al. / Environment International 63 (2014) 149–162 in this case study did not consider all the aforesaid listed 9 elements in a holistic and categorical fashion. As for other case studies, in some cases landﬁll liners, capping, and site area were main considerations (Depountis et al., 2009; Ganatsiou, 2006) which can only become part of 1-viii above; some cases focused on communities' distance and direction from landﬁlls (e.g. Sarkar et al., 2003) – which can contribute to the topography section of the baseline study; others considered environmental monitoring of leachate (e.g. Abu-Zeid et al., 2004) which can feed into the site management section of the baseline study; some cases took account of soil stratigraphy of landﬁll sites (e.g. Aderemi et al., 2011) – which can constitute geology section of the baseline study. Similarly, landﬁll risk assessment models (such as LandSim and HELP) address the baseline study predominantly in the hydrogeological context along with other associated aspects (Environment Agency, 2003d; Golder Associates, 2012; SSG, 2012) but not include all the 9 elements listed above in a categorically systematic manner. Thus, different case studies of landﬁll assessments have appeared to account for different aspects of baseline study. In a way, they contain a ‘mix and match’ of various baseline study elements and aspects (listed above), and none presents or applies a holistic baseline study system. One simple reason for this is that there is no such holistic system in place. There are a number of future needs of risk analysis that are required in order to respond to the new waste and resource management agenda (Pollard et al., 2006), and holistic baseline study for landﬁll leachate risk assessment is one of them – where a holistic baseline study system includes not only the eight modules indicated in Fig. 1 but also other aspects listed in Section 3.2 of the paper. With the way in which environmental legislation is becoming more integrated and inclusive (Section 3.3), current non-holistic and non-integrated baseline study approaches are not going to be sufﬁcient in the future to carry out landﬁll risk assessments with satisfactory level of completeness. 3.3. Current and future legislation With reference to the ‘state-of-the-art’ (indicated in Table 2), the current procedures used regarding risk analysis and baseline study, particularly for landﬁll, appear to be just sufﬁcient to meet the current legislation requirements (such as drinking water standards). The literature review reveals that predominantly only humans have been considered as receptors (See Table 2). There is clearly a lack of attention given to other potential receptors in a holistic manner, for instance: • Receptors other than humans such as aquatic and terrestrial ﬂora and fauna (e.g. crops and ﬁsh); • Natural environment consisting of various environmental media (e.g. land/soil, air, watercourses/groundwater); • Built environment comprising human-made ponds, buildings, residential houses, utility networks, playgrounds, entertainment centres, etc.; • Water courses, other than those used by humans for drinking, such as rivers of various water grades (SI, 1994b); and • Insufﬁcient consideration of multiple exposure routes and multiple exposure media of landﬁll leachate (such as dermal contact, ﬁsh contamination, bioaccumulation in plants, and food-web chain). The features listed above in Sections 3.1 and 3.2 become increasingly more important, both individually as well as collectively, when considering the implementation of new environmental ‘legislative instruments’ that nowadays already are and also are becoming more stringent, versatile, inclusive, and integrated. For instance, with reference to Table 1, the Water Framework Directive (EC, 2000), which has been employed in the UK, includes new requirements for protection and restoration not only of ground waters but also surface waters and their dependent ecological systems (Environment Agency, 2003a). Another directive, which is generally referred to as the ‘Habitat Directive’ (EC, 1992), speciﬁes a legal obligation to combat hazards in order to guard and enhance natural habitats and wild fauna and ﬂora. The Landﬁll Directive emphasises protection of not only hydrosphere, but also lithosphere, and atmosphere (i.e. quality of waters, soils and air is to be collectively guarded from landﬁll pollution). Thus, a more inclusive and integrated approach towards risk analysis is required. This requires that a baseline study be more integrated and strategic, as without a holistic baseline study, a complete risk analysis is not possible. Although these directives appear to be relatively old but it takes years for them to ﬁlter down, be interpreted and then implemented by member states. This also includes transitional periods and intermediate phases of implementation. Thus, all this takes substantial amount of time. These directives have been and are being implemented via a range of new regulations and guidance documents (e.g. DEFRA et al., 2011, Version 3.2, page 3). Whereas, old regulations are continually being revised based on feedback from consultancy, industrial and public/ government sectors, and other appropriate stakeholders. For example: Environmental Permitting Regulations 2007 (SI, 2007) was revised by the 2010 version (SI, 2010), which has now been even further upgraded by the Amendment Regulations (SI, 2011); similarly the oldest version of Waste Management Licensing Regulations was 1994 (SI, 1994a) and the latest so far is the 2005 regulations (SI, 2005); the Groundwater Regulations 1998 (SI, 1998) has now become the Groundwater Regulations 2009 (SI, 2009). 4. Concluding discussion While the current and forthcoming legislation pushes forward to reduce both the quantity of disposed wastes and the environmental impacts of landﬁll sites, there is still need to manage the current landﬁll sites and ﬁnd solutions to remediate and control environmental pollution from these sites. Furthermore according to the sustainable Waste Hierarchy, although waste amounts are to be reduced that are disposed of at landﬁlls, it is still not possible to have a ‘no-landﬁll’ society for a number of reasons: for instance, waste production cannot be reduced to zero in every scenario. Commodities cannot be reused and/or recycled all the time e.g. paper after recycling a number of times becomes nonrecyclable as paper ﬁbres deteriorate every time it is recycled. Not all waste can be composted or incinerated. Even the incineration of wastes leads to other wastes (e.g. ashes) being generated (though in much reduced amounts), which generally end up in landﬁll. Thus, landﬁll is inevitable. In other words, number of landﬁll sites may be reduced via efﬁcient waste management but not as low as zero to deliver a totally ‘landﬁll-free’ environment or a ‘zero-landﬁll’ society. Thus, despite having potential to pollute the environment, landﬁll is not entirely avoidable: some sites are necessary. Therefore risk assessment is necessary as an effective tool to guard the environment against landﬁll hazards. To the contrary, there does not exist as such an integrated and uniﬁed methodology of landﬁll risk analysis, which could assist performing the process of risk assessment for landﬁll leachate from the start (i.e. baseline study) through to the end (i.e. hazard indices and risk quantiﬁcation) – See Fig. 1. A number of knowledge gaps have been identiﬁed in the literature reviewed to date and a holistic baseline study system is one of them. The baseline study is not only the most signiﬁcant factor but also the most fundamental initial stage of an effective risk analysis, as the success of the latter is based on the former. The paper has established this not only by deﬁning the baseline study in landﬁll leachate context but also indicating implications and scope of the baseline study. The adequacy of a baseline study lies in effectively generating a holistic foundation consisting of relevant data and information to support a speciﬁc risk assessment. This needs to be done as quantitatively as possible to characterise a given landﬁll and constitute quantitative aspects of the risk assessment. This data and information for a speciﬁc landﬁll be collected and organised (i.e. collated) in such a format that the contents of the baseline study are systematically and categorically laid down to readily correspond to the following stages of the risk analysis process T.E. Butt et al. / Environment International 63 (2014) 149–162 of the landﬁll. The main conclusion of the overall assessment of the literature is that such a baseline study methodology (or even a complete guidance note) in such an algorithmic format does not exist that could be used as a ‘one-stop-shop’ by landﬁll risk assessors. Current risk analysis approaches are just adequate to meet the criteria and standards of the present environmental legislation, particularly in the UK. Legislation is increasingly growing to be more stringent and also wider in scope to encapsulate more environmental aspects and species (such as various food chain links, ecological systems, terrestrial and aquatic ﬂora and fauna). Furthermore, landﬁll leachate has great potential to (either directly or indirectly) pollute lithosphere (land/ soils), atmosphere (air), hydrosphere (water), and even any combination of these. These three fundamental constituents of the environment are also the main media of contaminants transport. Therefore a more comprehensive, concise, and robust risk analysis system – covering these three principal media – is required. This necessitates a correspondingly more strategic baseline study system with a wide ranging elements and features (indicated in Section 3.2). Via an exhaustive literature review as evident from the referent list, this paper recognises the need and signiﬁcance of baseline study as a whole-system approach and identiﬁes knowledge gaps. Although it is not in the scope of the study to develop a full-on baseline study system in a holistic manner, still the paper outlines bases for developing an algorithmic framework of such a holistic baseline study procedure which is integrated, coherent, comprehensive, inclusive, uniﬁed, sequential, offers consistency, and yet particularly for landﬁll leachate. The paper clearly lists downwide-ranging elements and features that need to be drawn together in order to form such a whole-system architecture of baseline study in the future. This way the paper paves a path for further research and development in the ﬁeld of risk assessment, speciﬁcally in connection to baseline study. Acknowledgements The authors acknowledge the ﬁnancial support of Dundee City Council which made this research study possible. We are additionally grateful for the discussion and help received from Mr Peter Goldie of the Environment & Consumer Protection Department, Dundee City Council. The support from Mr Stephen T. Washburn (CEO, ENVIRON, New Jersey, US), Dr I. M. Spence (Consultant Environmental Geologist, Scotland), and colleagues at the University of Abertay Dundee, including Dr Olisanwendu Ogwuda, Dr Kehinde O. K. Oduyemi, and Mr Phillip Jenkins is also highly appreciated. 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